Conventionally, a rubber (nitrile rubber) containing an α,β-ethylenically unsaturated nitrile monomer unit and a conjugated diene monomer unit or an olefin monomer unit has been known as a rubber having excellent oil resistance, and a cross-linked product thereof has been used as a material for a rubber product around various oils mainly for an automobile, mainly such as a fuel hose.
In this application, excellent oil resistance is also an important requested matter. Recently, due to growing global environmental protection activities, efforts to reduce the transpiration amount of a fuel such as gasoline into the atmosphere have advanced. For example, in Japan and Europe, NOx emission is regulated, and reduction in the transpiration amount of a fuel is required along therewith. Therefore, in an application such as a fuel hose or a fuel seal, low gasoline permeability, that is, better gasoline permeability resistance is required.
For example, in Patent Literature 1, by cross-linking a nitrile rubber composition obtained by adding an inorganic filler having a predetermined aspect ratio, a predetermined amount of a coupling agent, and a predetermined amount of a glycol compound to a nitrile rubber containing a predetermined amount of an α,β-ethylenically unsaturated nitrile monomer unit, a cross-linked rubber product suitable for a fuel hose is obtained.